Researchers believe that the movement of liquid metal in the Earth’s core is one of the main causes of geomagnetic reversal.
The Earth, a rocky planet with liquid water, is an ideal place for life to thrive for many reasons. It is situated at the right distance from its star for liquid water to exist on its surface. The gravitational pull of other planets protects Earth from the risk of collisions with wandering meteors. The magnetic field surrounding the Earth also provides a protective barrier for life against charged particles traveling through space, according to Space.
Experts cannot accurately predict when the Earth’s magnetic field will reverse. (Image: Space).
The Earth’s magnetic field is generated by the complex flow of molten metallic material in the planet’s outer core. This flow is influenced by both the rotation of the Earth and the existence of the solid iron core. As a result, a dipole magnetic field is formed with its axis aligned with the planet’s rotational axis. Hidden within the chemical composition of ancient rocks is evidence that the Earth’s magnetic field is a dynamic phenomenon. When lava cools, the iron minerals within it align with the Earth’s magnetic field, much like a compass needle pointing north.
The Earth’s magnetic field changes over very short and extremely long timescales, ranging from a few milliseconds to several million years. The interaction of the magnetic field with charged particles in the cosmos can alter it in the short term, while longer-term disturbances in the magnetic field are caused by processes in the Earth’s outer liquid core.
Influenced by the movement of fluids inside the Earth, the process of geomagnetic reversal can be divided into three stages.
- In the decay stage of the magnetic field, its intensity gradually weakens, and its direction becomes more chaotic.
- Next, geomagnetic drift is the process by which the magnetic poles begin to shift from their current positions and move in the opposite direction.
- The magnetic pole regeneration process is the stage where a new magnetic field begins to establish itself, with the poles ultimately reaching positions opposite to their previous locations.
Studies of the previous states of the magnetic field indicate that two polar states can exist. In the current normal state, magnetic field lines radiate out from the North Pole and enter at the South Pole. A reversed polarity state can also occur and be just as stable. Paleomagnetic studies indicate that the geomagnetic reversal of the Earth’s magnetic field is not periodic and cannot be predicted, primarily due to the mechanisms that generate it. According to geophysicist Leonardo Sagnotti, the flow of liquid metal (mostly molten iron) in the Earth’s outer core is highly chaotic and erratic. The geomagnetic reversal occurs during periods of low geomagnetic intensity and unstable magnetic field structures.
The period of magnetic pole repositioning lasts for several thousand years. When the magnetic field is about to reverse, it is in a weakened state, leading to increased exposure of the Earth’s atmosphere to solar winds and cosmic rays in the form of charged particles. Recent studies indicate that during the Laschamp geomagnetic reversal event 41,000 years ago, the amount of cosmic rays reaching the Earth’s atmosphere globally was three times higher than today.
For human civilization, the concern is not the change in the magnetic poles but rather the period of declining geomagnetic intensity. Modern society increasingly depends on technology. A large influx of charged particles entering the atmosphere at lower altitudes will impact security, communication, electrical infrastructure, satellites, and astronauts living in low Earth orbit. Particularly, due to the random nature of magnetic fluctuations, researchers cannot accurately predict when this will happen.
